Here’s the latest reader question, along with my reply!
Jeremy asks: I know that cold temperatures cause an EV’s range to plummet, even if not using the heater. My question is whether a battery will take a full charge in cold weather. What I’m curious about is whether the available KWh after a full charge will increase when it gets warm. In other words, does cold weather limit the charge capacity of the battery. I’ve searched for an answer but can only find info on range loss, not battery capacity.
My reply: My understanding is that most EVs have a thermal management system – including a battery heater as well as a battery cooling system – to maintain the battery pack’s temperature within a range such that it isn’t damaged by excessive heat or unable to be recharged due to excessive cold. They are also “managed” to accept charge at a certain rate – to avoid damage (and fire- hopefully). This is why EV battery packs don’t fully recharge at “fast” chargers in the time advertised.
So, assuming the EV does have a thermal management system, I would expect that it can take the same charge regardless of ambient temp but that the degree of warm or cold outside will affect the rate at which the available charge is depleted.
If it’s very cold out, the EV will be running its heater – even as you charge – so it will be discharging even before you begin driving. If it’s very hot out, then the system would be working to keep the battery pack cool – also drawing electricity.
This is just another of the serial problems with EVs for which there is no IC analog. It’s 17 degrees here in the Woods of SW Virginia today and the Ford Escape press car I have sitting in my driveway isn’t much if at all affected by this. It may take a couple of minutes longer to warm up, but there’s very little “energy penalty” to pay due to to the cold and no range penalty to pay for running the heater at full tilt because – as you know – in an IC car, the heat is basically free, energy-wise. The cabin is warmed by the cast-off heat of the running engine.
Even using the AC when it’s very hot out has little effect on an IC car’s range whereas using the AC in an electric car does.
And, of course, even if using the heat and AC reduced an IC car’s range by 25 percent it wouldn’t matter much in practical terms because the IC car can be refueled easily and quickly whereas the EV…
Sigh. And they ask me why I drink!
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